In the last few decades a wide range of reagents and techniques for transferring genetic material into cells for the purpose of modulating gene expression both in vitro and in vivo have been developed. Most efforts in this field are focused on the search for systems with greater efficiency and on new applications. These efforts have allowed obtaining sophisticated reagents and useful technologies for producing proteins with clinical and research applications, for adding genetic markers to a cell line and for modifying the protein expression of a cell to evaluate the effect of a gene (overexpression or reduction of expression).
Gene therapy is a very promising therapeutic tool for treating a wide range of hereditary or acquired diseases. Recent advances in molecular biology and knowledge of the human genome have allowed making valuable information on cell processes and the pathogenesis of many diseases available. In the last few years many genes involved in pathological processes have been identified; furthermore expression systems of those genes are being widely investigated so they can be used for therapeutic purposes. However, the development of new therapeutic strategies using this biological material depends on the capacity for manipulating the expression of these genes in suitable cells.
The number of diseases which can potentially be treated by means of gene therapy is very large, and they include among others, autosomal recessive diseases due to the defect of a single gene (cystic fibrosis, hemophilia, Fabry disease, etc.), autosomal dominant diseases, some cancers, HIV and other infectious diseases, inflammatory diseases, etc.
Gene therapy consists of introducing genetic material (DNA, RNA or antisense sequences) into target cells for the purpose of modulating the expression of specific proteins which are altered, thus reversing the biological disorder causing the alteration thereof. Naked genes can be locally administered into specific organs such as the muscle or liver by physical means such as electroporation or hydrodynamic injection. However, these methods are not useful for systemic administration or are nonviable from the viewpoint of marketing them as drugs. To develop a gene therapy product, not only the disease to be treated and the therapeutic gene to be administered must be taken into account, rather what is very important is the administration system of that gene. It is necessary that the administration system is capable of protecting the genetic material against enzymatic degradation and that it facilitates the cell uptake and subsequent release in the cell cytoplasm. Furthermore, it must allow controlling the localization of the gene in the organism as well as the duration of the gene expression. The gene administration systems can be classified as viral or non-viral vectors. The viral vectors are the most effective, but have large immunogenicity and oncogenicity problems. Another drawback is that they can only include small-sized genes.
Due to the drawbacks of these viral transfection systems, there is a serious need for developing non-viral transfection systems with a suitable transfection efficacy entailing an alternative better than using the viral vectors. The non-viral vectors are in fact much safer, their production is simpler and cheaper and do not have limitation in terms of the size of the genetic material to be included. In this sense, the nanoparticle-based systems have shown to be useful as transfection systems. Thus, application US2008/0160096 describes the production of nanoparticles based on complexing a polycation with one or more nucleic acids, said complex being coated with a polyanion. Application WO2007/135164 in turn relates to the preparation of nanoparticles based on chitosan and hyaluronan for associating genetic material, its particular use for transfecting ocular tissue being demonstrated.
In the literature there are also several documents which describe obtaining and using lipid nanoparticles as vectors for transporting genetic material to cells (WO2005/120469, WO2006/087752, WO2004/096140 and US2008/0213350). The document of Del Pozo-Rodriguez et al. (J. Control. Rel., 2009, 133, 52-59) particularly refers to a lipid nanoparticle system further incorporating ionic surfactants, where said nanoparticles are contacted with a complex made up of a plasmid and a peptide for coating the latter. Lipid nanoparticles also incorporating a peptide therein are described in WO000/06120. Application US2006/0189554 in turn describes a vaccine incorporating a lipid nanoparticle system on which surface there is deposited an adjuvant, a DNA plasmid being subsequently adsorbed. Nevertheless, the main drawback of many of these systems is a low transfection efficacy.
In view of these data, there is therefore a need to develop gene therapy drugs based on safe non-viral vectors and with a suitable transfection efficacy.